The goals of the Human Cancer Serology Program are: (1) Determine the role of viruses in the etiology of human cancer; (2) detect and analyze humoral immune reactions to cancer cells in patients with cancer; (3) identify characteristic human tumor antigens with heteroimmune sera for the purpose of developing immunodiagnostic methods for early cancer detection. In approaching these goals, a group with expertise in the techniques of virology, serology, cell culture and biochemistry has defined seven specific projects. They are: (a) Serovirological studies of Kaposi's sarcoma, with emphasis on the suspected etiological role of cytomegalovirus; (b) search for interspecies antigens of mammalian leukemia-sarcoma viruses (oncornaviruses) in human cancer with immunofluorescence, absorption, and radioimmunoassay techniques; (c) preparation of serological reagents to human papovaviruses to determine whether these viruses are involved in the etiology of tumors of the CNS and urinary tract, as well as of tumors occurring in patients with primary immunodeficiency disease; (d) definition of a group-antigen of herpesvirus, its serological relatedness to mammalian oncornaviruses, and its possible occurrence in human cancer; (e) detection and analysis of humoral immune reactions to cell surface antigens of melanoma and renal cancer; (f) analysis of a new intracellular antigen (P5NA) of osteogenic sarcoma, and seroepidemiology of the P5NA antigen and antibody in normal individuals and in patients with cancer and other diseases; and (g) characterization of the antigens of ovarian cancer with heteroimmune sera, and determination of the frequency and biochemical nature of anomalous blood group-like antigens in ovarian cancer. These studies are intended to provide fresh insights into the etiology, diagnosis, and therapy of human cancer.